1. Field of the Invention
This invention relates generally to compositions and methods for combating kidney disease and improving kidney function and particularly to the use of food compositions for preventing and treating kidney disease and improving kidney function.
2. Description of the Prior Art
It has been postulated since 1956 that the production of active oxygen species or free radicals during aerobic respiration results in oxidative damage that hastens aging and death in animals (Beckman, K., et al., “The Free Radical Theory of Aging Matures,” Phys. Rev., 78: 547-581 (1998)). Active oxygen species cause aging through various mechanisms, including directly damaging cellular DNA (Cutler, R., “Antioxidants and aging”, Am. J. Clin. Nutr., 53: 373S-379S (1991) and lipids and proteins (Tylicki, L., et al. “Antioxidants: A Possible Role in Kidney Protection,” Kid. Bl. Press. Res., 26: 303-314 (2003)). Free radicals, often produced in the mitochondria, where aerobic respiration occurs, damage mitochondrial DNA, proteins, and lipids, e.g., U.S. Patent App. Pub. No. US 2003/0060503.
It has also been postulated that active oxygen species may play a role in causing kidney disease (Ongajooth L., et al. “Role of Lipid Peroxidation, Trace Elements and Antioxidant Enzymes in Chronic Renal Disease Patients,” J. Med. Assc. Thai., 79:791-800 (1996)). Several mechanisms have been proposed to account for this increase in renal failure, e.g., Hasselwander, et al. “Oxidative Stress in Chronic Renal Failure,” Free Rad. Res. 29:1-11 (1998), Shah, S., “The Role of Reactive Oxygen Metabolites in Glomerular Disease,” Annu. Rev. Physiol., 57:245-62 (1995)), but scientific studies to date are inconclusive regarding whether antioxidant treatment is beneficial to those with kidney disease. Some studies indicate that there is a role for various antioxidant supplementations in the protection against kidney disease, e.g., Kedziora-Kornatowska et al, “Effect of Vitamin E and Vitamin C Supplementation on Antioxidative State and Renal Glomerular Basement Membrane Thickness in Diabetic Kidney”, Nephron Exp. Nephrol., 95:e134-e143 (2003). Other studies note the potential pro-oxidant properties of antioxidant supplements, concluding that there is not yet enough experimental evidence to recommend antioxidant supplements to alleviate kidney disease, e.g., Tylicki.
However, despite years of studies and developments relating to kidney disease and renal function, kidney disease and poor renal function remain a major health problem. There is, therefore, a need for new methods and compositions for preventing and treating kidney disease and for improving kidney function.